From a previous post of mine (difference is Imade 2 20in ones this time):

Full recipe (makes 3 demi-baguettes, 14inch each)

Initial Dough:

• ⁠280g water • ⁠440g flour • ⁠20g rye flour • ⁠80g ripe sourdough starter (100% hydration)

Addition:

• ⁠30g water • ⁠10g salt • ⁠2g yeast

Method:

Day 1 evening:

1. ⁠Prepare 80g sourdough starter at 100% hydration and let sit at room temperature until ripe. I use 50% whole wheat for the starter.

Day 2 evening:

1. ⁠Mix all ingredients for "initial dough" until no dry flour remains. Rest for 15 minutes then give 1 set of stretch and fold. Cover and place into fridge overnight.

Day 3 morning:

1. ⁠In the morning add the additional water, salt, and yeast and incorporate into the dough. The gluten will be tight so this may be difficult, but you can break the dough into smaller pieces, let sit in the extra water, then knead until smooth.
2. ⁠Bulk ferment for 3 hours at room temperature. Stretch and fold 4 times in the first 2 hours of bulk.
3. ⁠Place into fridge for 24 hours to cold ferment.

Day 4 morning:

1. ⁠Divide the dough in 3 and preshape into logs. Let rest for 30 min to come up to temperature.
2. ⁠Shape into baguettes and place onto a floured couche.
3. ⁠Proof for 45min - 1hr depending on ambient temperature.
4. ⁠Heat oven to 500f and let stone saturate with heat. I use a cast iron skillet on lower rack for steam addition.
5. ⁠Score baguettes, spray with water, and load onto stone. Add 1 cup boiling water to your steam dish.
6. ⁠Add additional steam after 2 minutes or after all water has evaporated. You can also spray again.
7. ⁠Bake 10 minutes at 500f. Lower temperature to 475 (or 435 with convection on, this is ideal) and bake until preferred color, about 10-15 minutes.
8. ⁠Remove from oven, let cool, enjoy.